This invention generally relates to protective enclosures and more particularly to an apparatus for protecting a lock from the environment and unauthorized access.
It is common practice to use a key operated padlock to secure the doors on cargo carrying trailers and vans to prevent unauthorized access to the cargo compartments. One common latch assembly used on such doors includes a vertically oriented bar which is slidably mounted in a housing on the exterior surface of the door and which can be extended into cooperating holes in the door frame so as to secure the door in a closed position. The bar is operated by a locking lever which is pivotally mounted to bar housing. The latch assembly also includes means for fixing the locking lever in the locked position including a resting bracket and a pivotally mounted keeper, both of which are attached to the door.
In order to lock the door, the door is first closed and then the lever is rotated upward into a horizontal position causing the locking bar to extend downward into the door frame. Next the keeper is rotated from the vertical sufficiently that the lever can be positioned into the rest bracket and then allowed to return to a vertical position. Finally, the shackle of a padlock is passed through cooperating openings in the lips of the keeper and rest bracket and the lock is closed. A latch assembly of this type is well known to those of ordinary skill in the art.
Because the padlock is exposed to the environment, a number of problems are encountered during operation. One such problem is that during winter driving conditions the locks are directly exposed to precipitation and road spray which may freeze, making the lock very difficult to open. In order to operate trucking lines efficiently it is necessary to minimize turnaround time at terminals. If the truck arrives with a frozen lock the terminal operators may simply resort to cutting the lock off rather than attempting to thaw it. Under other driving conditions the locks are exposed to considerable amounts of dust and dirt which may eventually cause the internal mechanisms to fail.
Another significant problem encountered by trucking lines is theft. With the type of latch assemblies described above the simplest way to gain access to the cargo compartment of a truck is to cut the shackle of the padlock. Numerous mechanical type protection devices for such padlocks are found in the prior art but most of them can be defeated in a few minutes by a thief with simple burglary tools. Also, many of them are undesirable in that they further complicate operation of the locking assembly and are themselves subject to freezing in winter conditions.
Accordingly, it is the object of this invention to provide for a protective device for padlocks used on truck cargo door locking assemblies and similar applications which will shield the padlock from the environment and yet not unduly complicate or hinder its operation.
It is a further object of this invention to provide for a simple and inexpensive alarm system which will warn of unauthorized access to the padlock and in doing so deter theft.